Exam 2: Auditory

Question 1

Amplitude

Answer 1

psychological experience of loudness measured in decibels (dB).

Question 2

Frequency

Answer 2

number of cycles of a wave per unit time.–Frequency in Hz (f)–Period of cycle(T)–f=1/T. The higher the frequency, the higher the pitch of the sound

Question 3

Outer Ear

Answer 3

Pinna, Auditory meatus, Tympanic membrane (eardrum)

Question 4

Middle Ear

Answer 4

Oval Window, Ossicles: Must transmit sound energy from air to fluid –boost pressure by focusing force onto small diameter of the oval window

Question 5

Inner Ear

Answer 5

Pressure waves converted into neural impulses

Question 6

Mechanoelectrical transduction

Answer 6

(One row of inner hair cells and three rows of outer hair cells, Each hair cell contains many stereocilia with one taller kinocilium, Tiplinks connect the tips of adjacent stereocilia)
Pivot point of the basilar membrane offset from pivot point of the tectorial membrane
basilar membrane displaced àtectorial membrane moves across the tops of the hair cells then stereocilia bend.
K+ ions flow into the hair cell down their electrochemical gradient., Voltage-gated Ca++channels open, Calcium enters, Release neurotransmitter, Graded potentials

Question 7

How is frequency information stored?

Answer 7

Low-frequency sounds excite basilar membrane motion near the apex.
High-frequency sounds excite basilar membrane motion near the base.

Question 8

Labeled Line

Answer 8

Labeled line code from inner hair cell through the midbrain and out to cortex, arrangement maintains a “Tonotopic” map –Place code

Question 9

Phase Locking

Answer 9

Hair cells oscillate opening and closing of cation gates in synchrony with incoming stimulus –i.e. hair cell membrane voltage oscillation encodes stimulus frequency (

Question 10

How is amplitude information stored?

Answer 10

At higher amplitude stimuli, the efficiency by which the inner hair cell can stimulate the afferent fibers is increased.

Question 11

Rate Code

Answer 11

Larger hair cell depolarization per single pressure wave event, How many hair cells respond to a given stimulus

Question 12

Population Code

Answer 12

The higher amplitude of a stimulus, the wider the region of basal membrane is disturbed by the pressure wave

Question 13

Characteristic Frequency

Answer 13

The frequency that the neuron responds at the lowest amplitude

Question 14

What is the function of outer hair cells?

Answer 14

the sharp tuning curve in the basilar membrane response
otoacoustic emissions (sounds that come out of the ear)
the non-linear response of the basilar membrane vibration at very low frequencies

Question 15

Auditory pathway from cochlea primary auditory cortex:

Answer 15

Thalamus: Relay to cortex.
Inferior colliculus: Integration of binaural cues to form a map of auditory space.
Lateral leminiscus: Monaural pathways. Some cells signal onset or duration of sound, regardless of intensity or frequency.
Superior olive and associated nuclei: Detection of binaural cues, ITD and ILD.
Cochlear nuclei and superior olive: Afferent and efferent connections with cochlea

Question 16

ITD

Answer 16

Interaural time differences (ITD) result from the path length difference from a sound source to each of the two ears.

Question 17

ILD

Answer 17

Interaural level differences (ILD) Barn owls have one ear facing up, the other facing down. Sounds above the owl will sound louder in one ear, while sounds below the owl will sound louder in the other. Thus the difference in the level (aka volume) of the sound between the two ears changes with elevation.

Question 18

What is phase ambiguity? Why is it a problem? How does the auditory system deal with it?

Answer 18

Phase ambiguity is a consequence of the way in which timing information is encoded by the auditory nerve. Deals with it with convergence across frequency bands
Pure tone: multiple locations sound could be coming from
Increase Bandwidth: combine across pure frequencies to narrow down location

Question 19

Response properties of 2D cells in the ICX Tonotopic map in A1, EE and EI cells:

Answer 19

Each 2D cell in the ICX responds to a specific combination of azimuth and elevation

1. ILD detection in one brainstem circuit (LSO)
2. ITD detection in a different brainstem circuit (MSO)
3. Elimination of phase ambiguity in ICC-ICX projection
4. Combination of ITD and ILD information in ICX -> assembly of an auditory space map

Question 20

Broca’s area

Answer 20

ventral posterior region of the left frontal lobe, sends output to motor areas of cortex, **speech production

Question 21

Wernicke’s area

Answer 21

posterior and ventral to the auditory cortex, receives info from auditory and sensory, **language comprehension

Question 22

How do bats use echolocation to locate a target?

Answer 22

In the FM-FM area, comparison of the delays between emitted sonar pulses and their reflections permits the calculation of target range.In the CF/CF area, analysis of the Doppler shifts associated with the constant-frequency component of sonar emission leads to an estimate of target velocity.

Question 23

Doppler Shift

Answer 23

changes in frequency (sound or light) produced by a moving source with respect to an observer. Waves emitted by an object traveling toward an observer get compressed àhigher frequency as the source approaches the observer. Waves emitted by a source traveling away from an observer get stretched out àlower frequency

Question 24

Cortical auditory implants

Answer 24

dont fuckin exist